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Yanmar 2T75U Engine

The Yanmar 2T75U (often designated as 2T75U-N) is a compact, 2-cylinder, vertical, four-stroke cycle, liquid-cooled diesel engine. Manufactured in Japan, this model belongs to Yanmar’s legacy line of highly durable sub-compact industrial power units. It is primarily engineered for small agricultural tractors, such as the Yanmar YM142and GT14, alongside various light commercial machinery. The design prioritizes structural stiffness, low mechanical vibration, and exceptional fuel economy for sustained operations under load.

The cylinder head utilizes an overhead valve (OHV) layout. It features a traditional 2-valve per cylinder configuration (one intake valve and one exhaust valve per cylinder) actuated by pushrods and rocker arms via a gear-driven camshaft housed in the cylinder block. A manual decompression shaft mechanism is integrated into the cylinder head bonnet assembly to facilitate emergency cold-cranking and service manual rotation. Engine Displacement: 635 cc (38.8 cubic inches). Cylinder Bore: 75 mm (2.95 inches). Piston Stroke: 72 mm (2.84 inches).

Fuel System: This unit utilizes a classic swirl-chamber pre-combustion system design coupled with an indirect injection apparatus. The mechanical system incorporates a dedicated multi-plunger inline fuel injection pump assembly driven by the engine gear train. High-pressure fuel lines deliver fuel to individual throttle-regulated injection valves (nozzles) mounted in the pre-chambers. The fuel supply line features a sediment-bowl style fuel filter with a water separator. Engine speed and fueling parameters are governed by a mechanical all-speed flyweight governor integrated into the gear housing. Cold start assistance is provided via electrical glow plugs located in the pre-combustion chamber.

The engine uses a full pressure-feed lubrication system. Oil is pressurized by a trochoid-type oil pump driven directly by the crankshaft gear train. Pressurized oil passes through an external, spin-on, full-flow lubricating oil filter element before entering the main oil gallery to lubricate the main bearings, connecting rod bearings, and camshaft journals. Rocker arm mechanisms are lubricated via a separate oil feed pass leading up through the cylinder head block. Engine cooling is managed by a closed-circuit, forced-circulation liquid cooling system. A belt-driven centrifugal water pump forces coolant through the cylinder block and cylinder head water jackets. System temperature is regulated via a wax-pellet type thermostat that controls fluid flow to an external radiator fitted with a pusher or puller cooling fan.

General Technical Data

Engine Specifications

Engine Model ............... Yanmar 2T75U
Engine Type ............... 4-cycle vertical inline 2-cylinder liquid-cooled diesel
Number of Cylinders ............... 2
Cylinder Arrangement ............... Vertical in-line
Engine Bore, in (mm) ............... 2.95 (75.0)
Engine Stroke, in (mm) ............... 2.83 (72.0)
Displacement, cu.in (cc) ............... 38.8 (635.0)
Rated Engine Power, hp (kW) ............... 14.0 (10.4)
Rated Engine Speed, rpm ............... 2600
Low Idle Speed, rpm ............... 1300
High Idle Speed, rpm ............... 2825
Aspiration Type ............... Naturally aspirated
Compression Ratio ............... 23.0:1
Firing Order ............... 1-2
Combustion Chamber Type ............... Special swirl pre-combustion chamber
Direction of Rotation ............... Counterclockwise viewed from flywheel side
Cylinder Block Material ............... High-strength cast iron
Cylinder Head Material ............... Monoblock cast iron
Lubrication System ............... Full force feed pressure lubrication
Oil Pump Type ............... Trochoid gear driven pump
Oil Filter Type ............... Full-flow spin-on paper element
Cooling System ............... Forced liquid circulation with radiator
Water Pump Type ............... Belt-driven centrifugal pump
Cooling Fan Type ............... Suction or pusher indexing fan
Air Cleaner Type ............... Dry dual-element paper cartridge
Preheating System ............... Intake air thermo-start glow plug system
Exhaust Muffler Type ............... High attenuation expansion silencer
Starting System ............... Electric starter motor
Electrical System ............... 12V
Alternator Output ............... 15A or 35A

Fuel System

Fuel Injection Pump Type ............... Bosch type inline jerk pump unit
Injection Pump Manufacturer ............... Yanmar Diesel Engine Co
Plunger Diameter, in (mm) ............... 0.26 (6.5)
Plunger Cam Lift, in (mm) ............... 0.276 (7.0)
Fuel Injection Timing ............... 18 degrees BTDC
Fuel Injection Valve Type ............... Screw-in nozzle holder assembly
Injection Nozzle Type ............... Semi-throttle type pintle nozzle
Number of Nozzle Orifices ............... 1
Nozzle Orifice Diameter, in (mm) ............... 0.039 (1.0)
Initial Injection Pressure, psi (kg/cm2) ............... 2272 (160.0)
Fuel Feed Pump Type ............... Electromagnetic diaphragm pump
Fuel Filter Type ............... Spin-on cartridge with water separator
Fuel Tank Capacity, gal (L) ............... 3.43 (13.0)
Recommended Fuel Type ............... Diesel Oil No. 2-D or ASTM D975
Fuel Return Pipe Line Diameter, in (mm) ............... 0.236 (6.0)
Governor Type ............... All-speed mechanical centrifugal governor
Governor Spring Free Length, in (mm) ............... 1.77 (45.0)

Dimensions and Weight

Overall Length, in (mm) ............... 19.5 (495)
Overall Width, in (mm) ............... 16.1 (410)
Overall Height, in (mm) ............... 20.9 (530)
Dry Weight, lbs (kg) ............... 200 (91)
Wet Weight, lbs (kg) ............... 212 (96)

Maintenance Data

Service Information

Standard Compression Pressure, psi (bar) ............... 426.7 (29.4)
Minimum Compression Pressure, psi (bar) ............... 341.3 (23.5)
Cylinder-to-Cylinder Pressure Deviation, psi (bar) ............... 28.4 (1.96)
Oil Pressure at Rated Speed, psi (bar) ............... 42.6 to 56.8 (2.94 to 3.92)
Oil Pressure at Idle Speed, psi (bar) ............... 9.95 to 14.2 (0.68 to 0.98)
Standard Coolant Operating Temperature, F (C) ............... 167 to 194 (75.0 to 90.0)
Thermostat Valve Opening Temperature, F (C) ............... 160 (71.0)
Thermostat Full Open Temperature, F (C) ............... 185 (85.0)
Fan Belt Deflection Range, in (mm) ............... 0.394 to 0.591 (10.0 to 15.0)
Intake Valve Clearance (Cold), in (mm) ............... 0.0059 to 0.0079 (0.150 to 0.200)
Exhaust Valve Clearance (Cold), in (mm) ............... 0.0059 to 0.0079 (0.150 to 0.200)

Engine Oil and Coolant

Engine Oil Type .................. SAE 30, SAE 10W-30, or 15W-40
API Service Classifications ......................... CD, CE, CF-4
Engine Oil Capacity, Upper Limit, qts (L) ............... 2.43 (2.3)
Engine Oil Capacity, Lower Limit, qts (L) ............... 1.58 (1.5)
Coolant System Total Capacity, qts (L) ............... 3.70 (3.5)

Service Intervals

Change oil and filter ............... Every 200 hours
Inspect air cleaner ............... Every 50 hours
Replace air cleaner ............... Every 500 hours
Replace fuel filter ............... Every 250 hours
Valve clearance adjustment ............... Every 300 hours
Fuel system inspection ............... Every 300 hours
Change coolant ............... Every 1000 hours
Compression test ............... Every 500 hours
Clean radiator core ............... Every 200 hours
Inspect belt tension ............... Every 100 hours

Service Specifications

Cylinder Bore Inside Diameter, in (mm) ............... 2.9527 to 2.9531 (75.000 to 75.010)
Cylinder Bore Maximum Wear Limit, in (mm) ............... 2.9567 (75.100)
Cylinder Bore Out-of-Round, in (mm) ............... 0.0004 (0.010)
Cylinder Bore Taper Wear Limit, in (mm) ............... 0.0004 (0.010)
Con Rod Small End Bushing I.D, in (mm) ............... 0.8665 to 0.8673 (22.010 to 22.030)
Con Rod Small End Bushing Clearance, in (mm) ............... 0.0004 to 0.0016 (0.010 to 0.040)
Crankpin Outer Diameter, in (mm) ............... 1.7697 to 1.7705 (44.950 to 44.970)
Connecting Rod Big End Bearing Bore, in (mm) ............... 1.7717 to 1.7728 (45.000 to 45.030)
Connecting Rod Bearing Clearance, in (mm) ............... 0.0012 to 0.0031 (0.030 to 0.080)
Crankshaft Main Journal Outer Diameter, in (mm) ............... 1.9665 to 1.9673 (49.950 to 49.970)
Main Bearing Bore Inner Diameter, in (mm) ............... 1.9685 to 1.9697 (50.000 to 50.030)
Main Bearing Oil Clearance, in (mm) ............... 0.0012 to 0.0031 (0.030 to 0.080)
Crankshaft End Play, in (mm) ............... 0.0035 to 0.0071 (0.090 to 0.180)
Thrust Washer Thickness, in (mm) ............... 0.0787 to 0.0807 (2.000 to 2.050)
Piston Skirt Outer Diameter, in (mm) ............... 2.9496 to 2.9504 (74.920 to 74.940)
Piston to Cylinder Wall Clearance, in (mm) ............... 0.0023 to 0.0035 (0.060 to 0.090)
Piston Pin Bore Diameter, in (mm) ............... 0.8661 to 0.8665 (22.000 to 22.010)
Piston Pin Outer Diameter, in (mm) ............... 0.8657 to 0.8661 (21.990 to 22.000)
Piston Pin to Piston Pin Bore Clearance, in (mm) ............... 0.0000 to 0.0008 (0.000 to 0.020)
Top Ring Groove Width, in (mm) ............... 0.0787 to 0.0795 (2.000 to 2.020)
Second Ring Groove Width, in (mm) ............... 0.0787 to 0.0795 (2.000 to 2.020)
Oil Ring Groove Width, in (mm) ............... 0.1575 to 0.1583 (4.000 to 4.020)
Top Ring Side Clearance, in (mm) ............... 0.0025 to 0.0037 (0.065 to 0.095)
Second Ring Side Clearance, in (mm) ............... 0.0012 to 0.0025 (0.030 to 0.065)
Oil Ring Side Clearance, in (mm) ............... 0.0008 to 0.0022 (0.020 to 0.055)
Top Ring End Gap, in (mm) ............... 0.0079 to 0.0138 (0.200 to 0.350)
Second Ring End Gap, in (mm) ............... 0.0079 to 0.0138 (0.200 to 0.350)
Oil Ring End Gap, in (mm) ............... 0.0079 to 0.0157 (0.200 to 0.400)
Cylinder Head Surface Distortion Flatness, in (mm) ............... 0.0020 (0.050)
Cylinder Block Top Surface Distortion Flatness, in (mm) ............... 0.0020 (0.050)
Intake Valve Head Diameter, in (mm) ............... 1.1811 to 1.1850 (30.000 to 30.100)
Exhaust Valve Head Diameter, in (mm) ............... 1.1024 to 1.1063 (28.000 to 28.100)
Intake Valve Stem Outer Diameter, in (mm) ............... 0.2736 to 0.2744 (6.950 to 6.970)
Exhaust Valve Stem Outer Diameter, in (mm) ............... 0.2732 to 0.2740 (6.940 to 6.960)
Valve Guide Inner Diameter, in (mm) ............... 0.2756 to 0.2764 (7.000 to 7.020)
Intake Valve Stem-to-Guide Clearance, in (mm) ............... 0.0012 to 0.0028 (0.030 to 0.070)
Exhaust Valve Stem-to-Guide Clearance, in (mm) ............... 0.0016 to 0.0031 (0.040 to 0.080)
Valve Seat Angle, deg ............... 45
Valve Spring Free Length, in (mm) ............... 1.4961 (38.000)
Camshaft Journal Outer Diameter (Front), in (mm) ............... 1.5728 to 1.5736 (39.950 to 39.970)
Camshaft Journal Outer Diameter (Rear), in (mm) ............... 1.5728 to 1.5736 (39.950 to 39.970)
Camshaft Bearing Bore Inner Diameter, in (mm) ............... 1.5748 to 1.5760 (40.000 to 40.030)
Camshaft Journal Oil Clearance, in (mm) ............... 0.0012 to 0.0031 (0.030 to 0.080)
Intake Cam Lobe Height, in (mm) ............... 1.2953 to 1.2992 (32.900 to 33.000)
Exhaust Cam Lobe Height, in (mm) ............... 1.2953 to 1.2992 (32.900 to 33.000)
Camshaft End Play, in (mm) ............... 0.0020 to 0.0059 (0.050 to 0.150)
Rocker Arm Shaft Outer Diameter, in (mm) ............... 0.4717 to 0.4724 (11.980 to 12.000)
Rocker Arm Bushing Inner Diameter, in (mm) ............... 0.4728 to 0.4736 (12.010 to 12.030)
Rocker Arm Shaft-to-Bushing Clearance, in (mm) ............... 0.0004 to 0.0020 (0.010 to 0.050)
Tappet Lifter Outer Diameter, in (mm) ............... 0.8642 to 0.8650 (21.950 to 21.970)
Tappet Guide Bore Inner Diameter, in (mm) ............... 0.8661 to 0.8673 (22.000 to 22.030)
Tappet-to-Guide Bore Clearance, in (mm) ............... 0.0012 to 0.0031 (0.030 to 0.080)
Idler Gear Shaft Outer Diameter, in (mm) ............... 1.1791 to 1.1803 (29.950 to 29.980)
Idler Gear Bushing Inner Diameter, in (mm) ............... 1.1811 to 1.1823 (30.000 to 30.030)
Idler Gear Shaft-to-Bushing Clearance, in (mm) ............... 0.0008 to 0.0031 (0.020 to 0.080)

Tightening Torques

Cylinder Head Bolts, lb-ft (Nm) ............... 54.2 to 57.8 (73.5 to 78.5)
Connecting Rod Cap Bolts, lb-ft (Nm) ............... 23.1 to 25.3 (31.4 to 34.3)
Flywheel Retaining Bolts, lb-ft (Nm) ............... 57.8 to 61.4 (78.5 to 83.3)
Main Bearing Cap Bolts, lb-ft (Nm) ............... 54.2 to 57.8 (73.5 to 78.5)
Crankshaft Pulley Front End Nut, lb-ft (Nm) ............... 65.1 to 72.3 (88.3 to 98.1)
Camshaft Thrust Bearing Assembly Bolts, lb-ft (Nm) ............... 14.5 to 18.1 (19.6 to 24.5)
Rocker Arm Shaft Support Bracket Fasteners, lb-ft (Nm) ............... 14.5 to 18.1 (19.6 to 24.5)
Valve Cover Bonnet Seal Nuts, lb-ft (Nm) ............... 5.1 to 7.2 (6.9 to 9.8)
Timing Gear Case Front Housing Cover Bolts, lb-ft (Nm) ............... 14.5 to 18.1 (19.6 to 24.5)
Oil Pan Base Retaining Perimeter Fasteners, lb-ft (Nm) ............... 6.5 to 8.7 (8.8 to 11.8)
Oil Pan Bottom Drain Plug Fastener, lb-ft (Nm) ............... 36.2 to 43.4 (49.0 to 58.8)
Fuel Injection Pump Mounting Flange Nuts, lb-ft (Nm) ............... 14.5 to 18.1 (19.6 to 24.5)
Fuel Injection Nozzle Holder Assembly Base, lb-ft (Nm) ............... 36.2 to 43.4 (49.0 to 58.8)
Fuel High Pressure Delivery Line Union Nuts, lb-ft (Nm) ............... 18.1 to 21.7 (24.5 to 29.4)
Fuel Leak-off Return Line Overflow Banjo Bolt, lb-ft (Nm) ............... 7.2 to 10.8 (9.8 to 14.7)
Exhaust Manifold Nuts, lb-ft (Nm) ............... 18.1 to 21.7 (24.5 to 29.4)
Intake Manifold Flange Fasteners, lb-ft (Nm) ............... 14.5 to 18.1 (19.6 to 24.5)
Water Pump Assembly Drive Belt Housing Bolts, lb-ft (Nm) ............... 14.5 to 18.1 (19.6 to 24.5)
Thermostat Housing Cover Placement Bolts, lb-ft (Nm) ............... 14.5 to 18.1 (19.6 to 24.5)
Oil Pressure Switch Sensor, lb-ft (Nm) ............... 10.8 to 14.5 (14.7 to 19.6)
Coolant Temperature Thermistor Transmitter, lb-ft (Nm) ............... 14.5 to 21.7 (19.6 to 29.4)
Glow Plug Preheater Intake Manifold Base, lb-ft (Nm) ............... 14.5 to 18.1 (19.6 to 24.5)
Starter Motor Mounting Bolts, lb-ft (Nm) ............... 32.5 to 39.7 (44.1 to 53.9)
Alternator Pivot Charging Bracket Bolts, lb-ft (Nm) ............... 32.5 to 39.7 (44.1 to 53.9)
Alternator Adjusting Tensioner Arm Bolt, lb-ft (Nm) ............... 10.8 to 14.5 (14.7 to 19.6)
Flywheel Housing Rear Bolts, lb-ft (Nm) ............... 32.5 to 39.7 (44.1 to 53.9)
Oil Pump Assembly Base Bolts, lb-ft (Nm) ............... 14.5 to 18.1 (19.6 to 24.5)
Idler Gear Shaft Support Screw, lb-ft (Nm) ............... 18.1 to 21.7 (24.5 to 29.4)

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